Deficiencies: Tomatoes

Posted by: Alejandro Gutierrez

Home Growing, Hydroponics, Organic, Plant Nutrition, Science

Have you ever noticed your plants and crops not being the best version of themselves? Some common signs could be that you notice light green to yellowish leaves, very thin stems, brown roots along more worrying signs.

Plant nutrition plays a very important role in your plant’s development and capacity and ultimately health. Like humans, who demand a different nutrition regime throughout their different life stages and conditions, plants are no different when it comes to plant type and growing stage respectively. For instance, a tomato plant will demand different nutrient ratios compared to a pepper plant, an onion, and so on.

Like humans, when plants aren’t properly nurtured, they will be prone to disease due to nutrient deficiency. While other factors also play a role, such as the environment to mention one, the way we feed our plants is entirely up to us. Aside from being prone to disease, nutrient deficiency will impact the plant’s development, this includes a number of factors such as:

• Overall plant size and color
• Plant’s internal functions
• Yields
• Taste / Flavor
• Shelf-life
• Consistency

While some nutrient deficiencies are similar, others are not. Depending in the nutrient deficiency and the plant type, the symptom the plant will suffer. Here is a quick view of the different nutrient deficiencies in tomato plants.

• Nitrogen deficiency in tomatoes will reflect when older leaves turn chlorotic. If you are observant, you’ll notice how gradually the leaves will deteriorate. In the other hand, young leaves which will receive the available nitrogen will reflect in yellowish leaves. Overall the decomposition process in tomato leaves will go from an original vibrant green to light green to yellowish to chlorotic.

• Phosphorus deficiency in tomatoes can be seen in slow leaf growth, aside from the slow growth the leaves will gradually be composed of a dull green color, until they turn red/purple.

• Potassium deficiency in tomatoes can be easily identified by focusing in the leave’s edge, reflecting a burn. Further, the older leaves will be the first to display some chlorosis while the leaves veins will remain green. A deficiency in potassium can also directly impact the tomato fruit in the process of ripening.

• Calcium deficiency in tomatoes can be seen in the plant through interveinal chlorosis. Further, the tomato fruit will reflect the calcium deficiency in what is commonly known as blossom-end rot. (Frequently mistaken as a plant disease)

• Magnesium deficiency in tomatoes is most notable when the leaves develop interveinal chlorosis while the midrib of the leaf keeps green. As the deficiency progresses the interveinal chlorosis will become necrotic.

• Sulfur deficiency in tomatoes can be easier spotted from the stem. When a plant undergoes sulfur deficiency, the stem will become purple and thin. Aside from the stem, the leaves will reflect a light green.

• Boron deficiency in tomatoes will target older leaves first by turning them yellow and stiff, in which where the growing point will turn necrotic and eventually die. The edge and the tips of these older leaves will also become necrotic.

• Copper deficiency in tomatoes reflects first in the younger leaves through wilting. At the same time, the leaves may curl upwards while expressing a blue/green color.

• Iron deficiency in tomatoes will target younger leaves through interveinal chlorosis, if the deficiency persists, the leaves will then have a yellow color. However, the midrib of the leaves tends to stay green through the deficiency process.

• Manganese deficiency in tomatoes will be expressed by the development of interveinal chlorosis in the younger leaves, followed by necrosis. Like an iron deficiency, the midrib of the leaf will remain green

• Molybdenum deficiency in tomatoes is very rare, particularly because while important, the demand for this nutrient is somewhat low. Nevertheless, this deficiency is identifiable

• Zinc deficiency in tomatoes can be spotted by the leaf’s color when turning brown and/or orange, as well as the leaves tendency to curl downward  

There are a couple of reasons why nutrient deficiencies take place, for instance soil type. A balanced pH soil will allow easy mobility of nutrients but won’t guarantee all necessary nutrients are present, additionally, acidic (less than a pH of 6) or alkaline soils (greater than a pH of 7) will make nutrients immobile, making it harder for the plant to absorb, leading to deficiency. Further when feeding your plants, the excessive or unbalanced use of the applied plant nutrients can generate nutrient antagonism and deficiency. A final factor that may contribute to nutrient deficiency in your tomato plants would be environmental aspects as low temperatures, excessive moisture in your soil, as well as the compaction of the latter. 

To avoid negatively affecting your tomato plants, always aim to have a neutral pH in your soil, unless you’re growing hydroponically. Provide them with balanced nutrition, fulfilling the specific needs of your tomato plants throughout their different growing stages, and make sure to establish them in a thriving environment.